Elefseria

The first person to hold the title of Guild Master, and the founder of Magia Dragon. As a human, Elefseria appears as an old man with a wrinkled face, long white-grayish hair, and a drab of an old-style magician with a wizard's hat. As a dragon, he appears as a large, bearded dragon with horns, uniquely shaped arms and claws, as well deer-like antlers.

Elefseria appears as a jovial old man who has a perverted side. However, he can also be solemn and full with fortitude and gratefulness as such when he was dealing with Team Natsu and smiled at their vow to complete the quest he has posted for over 100 years.

In the year X633, Elefseria bore witness to countless Mages who were killed by those who believed Magic to be an evil power. He tearfully declared that Mages would need to be protected and united, thus forming Magia Dragon, the first Guild in the history of Earth Land. At some point in his life, he taught himself Dragon Slayer Magic in order to combat the Five Dragon Gods. As a consequence of overusing his power, however, he ultimately transformed into a dragon. Since then, Elefseria posted a job request for other Guilds that would go unfulfilled for over a century due to its immense difficulty with only Gildarts Clive returning home alive, gaining the designation of a "100-year quest".

(Source: Fairy Tail Wiki)